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5.18 Frame Building Part 4: Drilling water bottle boss




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This article is from the Misc Bicycles FAQs, by various authors.

5.18 Frame Building Part 4: Drilling water bottle boss


Dave had another custom tool they had recently constructed for drilling
the holes for the water bottle bosses. The water bottle boss holes need
to be centered on the tube, in the same line, and a the standard water
bottle cage hole distance apart. This isn't that easy given that the
tube is round. The tool they had consisted of a cylindrical block which
fit into the bottom bracket. From here there was an arm which was
parallel to the plane of the frame. Attached to the arm was a block
which rotated. The block was rounded to fit the shape of the tube and
it had two holes in it the right distance apart. All that was necessary
to do was determine where the holes should be drilled and then drill
through the holes in the block. To determine where the holes should be
drilled, they had a couple water bottle cages with bottles in them which
could be generally positioned on the tubes. I was trying to get two
cages in there for two large water bottles. A general rule of thumb for
the seat tube was that either the bottom hole had to be 160mm above the
bottom bracket shell, or if it was below that the top hole had to be at
160mm. The reason is otherwise the water bottle cage could interfere
with the placement of the front derailleur. The cage on the down tube
had to be high enough so as not to interfere with the cage on the seat
tube.


 

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